You can't build a RAID 0+1 with anything less than 4 drives, since 0+1 is "Striped sets (needing at least 2 drives per 'set'), in a mirror (requiring at least two 'sets')".
A bit of info from Wikipedia:
RAID 0+1: striped sets in a mirrored set (minimum four disks; even number of disks) provides fault tolerance and improved performance but increases complexity.
If your controller supports it, you may be able to get away with spanning/JBOD the two 1TB drives into one volume (or perhaps even striping/RAID0), and then mirror/RAID1 that volume with the 2TB drive.
As KCotreau suggested in his answer, you'll probably want to dig around in your chosen RAID controller's UI and/or documents and see what it can support.